Switching apparatus



Dec. 24, 1968 R. L. WILSON ETAL' 3,418,462

SWITCHING APPARATUS Filed Jan. 28, 1966 4 Sheets-Sheet 1 Inventors Rosser L. Wilson. Paul E. Redelmafu If? MM fi-H'ornegs Dec. 24, 1968 WILSON ET AL SWITCHING APPARATUS 4 Sheets-Sheet 2 Filed Jan. 28, 1966 T r... 6 a F7 6 n s Q m 7 W flrl 7 V J A;

Inventors Rosser LWilson. Paul E. Rede-lma rt- 35/ aux/pm aq-Hw rne 15,6

Dec. 24, 1968 R. 1.. WILSON ET AL 3,418,462

SWITCHING APPARATUS Filed Jan. 28, 1966 4 Sheets-Sheet S Inventors Rosser 1.7.Ul' [Son- Paul E Redelman. 35, and 3M )q'H orneqQ'S Dec. 24, 1968 w o ET AL 3,418,462

SWITCHING APPARATUS 4 Sheets-Sheet 4 Filed Jan. 28, 1966 Inventors RosserL. Wilson. Paul .E. RedelmarL United States Patent 3,418,462 SWITCHING APPARATUS Rosser L. Wilson, Mahwah, N .J., and Paul E. Redelman,

Chicago, Ill., assignors to Abex Corporation, a corporation of Delaware Filed Jan. 28, 1966, Ser. No. 523,688 11 Claims. (Cl. 246393) ABSTRACT OF THE DISCLOSURE Ln the event the switch points of a railroad switch encounter an obstruction in the course of movement between limit positions, a torque limiting clutch, of appropriate construction, actuates a switch incidental to conditioning the drive motor for a reverse operation, returning the switch points to their original position.

This invention relates to switching apparatus for shifting the switch points of a railroad switch.

The present invention is directed to apparatus for shifting railroad switch points between their limit positions. Typically, switch points are shifted in a number of ways. For instance, a manual hand throw lever is operated to turn a mechanism connected to a throw rod, which in turn is connected to the switch points for manually shifting switch points between limit positions. Another way involves power shifting of the switch points by some motor operated mechanism which is adapted to be controlled from a remote location such as a switching tower. Thirdly, a locomotive or car wheel trailing a switch moves its wheel flanges between the switch points to cause a shifting of switch points to the opposite position.

In automatic classification yards wherein the switches are remotely controlled to route cars to destinations on classification tracks, it is preferred that the switching ap paratus be operable by each of the above manners of operation, namely, by hand, by power operation or by a trailing wheel. With the advent of improved automatic control equipment in railroad classification yards, there is a need for high speed switching. This is particularly true where a number of switches are closely spaced to one another such that the switches must be quickly operated in sequence to accomplish the routing of closely following cars or cuts of cars moving therethrough. Thus, the switching apparatus must be capable of quick reversals to return the switch points to afford new switching routes. Accordingly, an object of the invention is to shift rapidly switch points of a railroad switch with a switching apparatus affording a plurality of modes of operation.

The switch points are exposed to the weather; and the switches must be moved rapidly against the resistance of ice, snow or other foreign matter, which matter tends to retard the throwing of the switch points, particularly at high speeds. Another factor with severe climatic conditions may be that of resistance to completely closing the switch. Thus, it is necessary to generate considerable force to drive the switch points quickly and to drive switch points completely to a limit position.

Accordingly, a further object of the invention is to drive in a positive fashion the switch points between limit positions with a force sufiicient to close the points under adverse conditions.

One conventional switching apparatus employs hydraulic apparatus for driving switch points between their respective limit positions. The present invention affords an alternative to the hydraulic mechanism in that the operating force may be supplied by an electric motor. When driving switch points back and forth between limit positions by an electric motor at a rapid rate, large motor torques must be applied quickly to drive the switch points Patented Dec. 24, 1968 against adverse climatic resistances. To avoid damage to the switch points or the switching apparatus, the motor drive torque may be limited or uncoupled when the switch points have moved through a distance to reach a limit position. Not only is the motor drive quickly interrupted when the switch points reach their limit position, but the motor drive must be capable of being quickly reversed to return the switch points. Accordingly, a further object of the invention is to drive the switch points positively with torque generated by an electric motor to quickly move the switch point from one limit position to the other and to rapidly reverse the switch points to the original position, if desired.

In the preferred form of the present invention, a commercially available switch stand such as that described in US. Patent No. 2,575,037, is connected to the switch points and is power operated by an electric motor. In switch stands of the aforementioned kind, a linkage in the switch stand must be moved through and precisely stopped in a given orientation so that the switch stand is capable of being trailed by a locomotive or car wheel as well as being manually operated. A characteristic of this switch stand is that it employs an overcenter linkage which moves in an arcuate path between horizontal orientations when actuated manually or by power drive. The overcenter linkage is stopped in a horizontal plane so that the linkage may be straightened and moved through a straight line orientation when a locomotive or car wheel trails the switch.

When the linkage is stopped in a precise or horizontal position, a strong biasing spring is compressed and maintains a biasing force on the switch points to hold them in a limit position against a traffic trail. In operation of the switch stand, the switch points are thrown positively to a limit position prior to completion of the 180 turning movement of the linkage; and the further turning of the linkage to the horizontal position compresses the strong biasing spring so that the biasing spring holds the switch points at their closed position thereby assuring that the switch remains closed. Accordingly, a further object of the invention is to power operate a switch stand having an overcenter linkage between predetermined orientations by means of an electric motor. A more specific object of the invention is to operate the electric motor and the switch stand so as to drive the switch points between their limit positions and then quickly interrupt the drive to prevent the driving of the linkage of the switch stand beyond a horizontal position.

Another object of the invention is to drive the switch points by an electric motor coupled to a switch stand by a torque limiting clutch which affords a positive drive to move the switch points between limit positions.

Another object of the invention is to drive a switch stand by an electric motor coupled to an epicyclic type gear mechanism, which may also be operated by a manually operable lever, to operate the switch stand to throw the switch points to a limit position. In one embodiment of the invention an intermittent cam device couples an electric motor and a gear mechanism for driving the switch stand, and this constitutes a further object of the invention.

A further object of the invention is to detect relative movements between the input and output portions of a torque limiting clutch to control operation of the motor for driving the switch points between limit positions. More particularly, a further object of the invention is to sense the relative movement of the input portion and output portion of the torque limiting clutch in order to de-energize a reversible electric motor and to condition the reversible electric motor for reverse rotation upon the succeeding energization thereof.

Another object of the invention is to prevent injury to an operator of the manually operable throw lever by disabling the electric motor from operating during a manual throwing of the switch points.

A further object of the invention is to detect failure of the switch points to reach a limit position, as for example, due to an obstruction; and to cause an automatic reversal of the electric motor to drive the switch points to their original position.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, shows preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIG. 1 is a diagrammatic plan view of a switch throwing apparatus constructed in accordance with the preferred embodiment of the invention for throwing switch points between railroad rails;

FIG. 2 is a perspective view of a railroad switching apparatus constructed in accordance with the preferred embodiment of the invention;

FIG. 3 is a partial view of a clutch using the switching apparatus;

FIG. 3A is an enlarged partial view of an arm engaging a stop and a micro-switch;

FIG. 4 is an enlarged view partially in section of a a differential gear drive;

FIG. 5 is another embodiment of the invention of a switch stand constructed in accordance with the principles of the present invention;

FIG. 6 is a switch apparatus constructed in accordance with a still further embodiment of the invention;

FIG. 7 is a partial sectional view of a switch stand employed with the switching apparatus;

FIG. 8 is an elevational view of the switch stand of FIG. 7;

FIG. 9 is a plan view of a differential driven by a geneva drive mechanism employed in a switching apparatus; and

FIG. 10 is a view taken along the line 1010 of FIG. 9 in the direction of the arrows.

Referring now to the drawings and more particularly to FIG. 1, there is illustrated a pair of railroad stock rails 10 and 11 secured to the usual railroad ties T. Between rails 10 and 11 are a pair of switch points 12 and 13 secured to one another by conventional rods 15 and 16 to hold the switch points 12 and 13 together so that they move as a unit between their limit positions against either the stock rail 10 or the stock rail 11. The switch points 12 and 13 are illustrated in FIG. 1 in the straight through position for railroad cars moving thereover.

For moving the switch points 12 and 13 between their limit positions, a switching apparatus 20, FIG. 1, is operatively connected by a connecting rod 22 to a throw rod 23, which in turn is connected to the switch points 12 and 13. The switching apparatus has a base plate B spiked otherwise suitably secured to the railroad ties T.

A conventional way of shifting switch points between limit positions is rotation of a manual throw lever of a switch stand which, in turn, is connected by a connecting rod to the switch points. In the preferred embodiment of the present invention, the switch points 12 and 13 may be shifted between either of their limit positions by the switch apparatus 20 upon turning a manual throw lever 26 through 180 between positions generally spaced above the ties T and in a general horizontal disposition, as shown in FIG. 2. The preferred switch stand, which will be described in greater detail hereinafter, is illustrated in FIGS. 7 and 8, and is commercially available switch stand, the operation of which has previously been described in US. Patents Nos. 2,575,037 and 3,127,138.

Briefly, the switch stand has a vertical spindle 31, FIG. 8, with a crank 30 connected to the connecting rod 22 and throw rod 23. Turning of the spindle 31 through turns the crank 30 to reciprocate the connecting rod 22 to cause shifting of the switch points 12 and 13 between limit positions. The spindle 31 is turned through 90 upon each turning through of spring base casting 34 at the left end thereof, FIGS. 2 and 8. The spring base casting 34 is turnable by an adapter 35 secured to a shaft 36 which is operable by the manual handle 26. The manner in which the turning of spring base casting 34 through 180 causes a turning of the spindle 30 and operation of the switch points 12 and 13 will be described hereinafter in detail.

An important aspect of the present invention is that the switch points 12 and 13 may be thrown between their limit positions by three varying modes of operation, namely, by operation of the manual throw lever 26, by operation of a motor means 38, FIG. 2, or by the flanges of a locomotive or car wheels trailing through the switch points 12 and 13. More specifically, under the principles of the present invention, it is possible for the switch points to be moved to their limit position by any one of the above modes of operation Without the need for any special conditioning of the switching apparatus 20 either before or after a switching operation.

One common installation for switching apparatus is in railroad classification yards wherein the switching apparatus is operated automatically from remote locations either by an operator or by automatic control equipment. With the advent of the electrical control equipment for switching yards, the speed of the switching operation has become increasingly faster. Thus, in some installations, it is desired that the switching points he moved between limit positions in a period of one-half second or less.

To move the switch points 12 and 13 between limit positions within 0.5 seconds or less, requires considerable torque to be generated by the motor means 38 and to be applied quickly to the switching points 12 and 13. Another reason for applying a large force for driving the switch points 12 and 13 is to assure that the switch points are moved to their limit positions even though the speed of operation of the switch points may be retarded by ice, snow, dirt, or other foreign matter. Not only do such climatic conditions tend to retard the rapid movement of the switch points, but also such conditions prevent the closing of the switch points at a limit position, particularly where the switch points are not positively driven by full force to a limit position.

The present invention assures the driving of the switch points in a positive fashion to a limit position and in an expeditious manner by use of a coupling means. In its preferred form, the coupling means takes the form of a torque limiting clutch 44, FIGS. 2 and 3, but may also be a geneva drive mechanism, FIGS. 9 and 10. In FIG. 2, the motor means 38 includes a motor 40 for driving a torque clutch 44 which in turn drives a chain 45, FIG. 2, to turn a sprocket 46 to operate gear means 48 to turn the shaft 36 to operate the spindle 31 of the switch stand. the limiting clutch 44 couples the driving torque provided by the motor 40 to the driving chain 45 which causes shifting of the switch points 12 and 13 to a limit position after which the torque builds up to a degree causing release of the torque limiting clutch 44. In this manner, the switch points 12 and 13 are driven positively to their limit positions; and after having reached their limit positions, the torque being applied as limited or alternatively, uncoupled, as will be explained hereinafter Preferably, the electric motor 40 is a reversible motor adapted for rotation in either direction. The motor 40 has a motor shaft 50, FIG. 2, which is connected to an input portion or side 51 of the torque limiting clutch 44. The torque limiting clutch 44 may take many forms, one of which is illustrated in greater detail in FIG. 3.

As best seen in FIG. 3, the torque limiting clutch 44 includes an input portion 51 and output portion 52. Each of the input and output portions 51 and 52 have inclined teeth 54, which are in meshed engagement with one another to transmit the driving torque from the motor shaft 50 to an output shaft 55 secured to the output clutch portion 52. The ouput shaft 55 is journaled for rotation in a supporting pillow block 57, FIG. 2, and has secured thereto a small sprocket 58.

A compression spring 59 on the shaft 50 bears against a fixed seat 61 afforded by a nut and washer, FIG. 3, and the opposite end of the spring 59 biases the input clutch portion 51 into mating engagement with the output portion 52 on the output shaft 55. The input portion 51 is keyed or splined by a key 62, FIG. 3, to rotate with the input motor shaft 50; but is free for axial sliding on the motor shaft 50. The spring 59 holds the clutch teeth 54 on the input portion 51 enmeshed with the teeth 54 on the output clutch portion 52 until a predetermined torque is generated. This predetermined torque is obtained with stopping of turning of the output shaft 55 while the input clutch portion 51 is being turned by the motor means 38. The input clutch teeth 54 then begin to slide along the output clutch teeth 54. That is, with build up of torque in the clutch to a predetermined amount, the teeth 54 cam against one another to force the input clutch portion 51 to slide leftwardly, FIG. 3, against the urging of the spring 59 along the shaft 50. Thus, the input clutch teeth 54 will become effectively disengaged with the output clutch teeth 54 when sufiicient torque is generated. In actual practice, the output and input teeth will engage and disengage until the motor is de-energized with the torque remaining applied to the output shaft 55 until the motor 40 is deenergized.

For the purpose of stopping the electric motor 40, a torque sensing switch means 65 has a finger 66 disposed adjacent the leftward edge 67 of the input clutch portion 51. Upon reaching the predetermined torque limit, the input clutch portion 51 moves axially of shaft 50 and operates the finger 66 to the dotted line position shown in FIG. 3, causing contacts in the limit switch 65 to break the electrical circuit for the motor 40. As the motor 40 slows down, the input teeth 54 of the clutch come to rest and engage in the output teeth 54 for the next operation. Preferably, each of the clutch teeth have inclined surfaces at a angle to facilitate the separation thereof. The nut and washer 61 are movable on the input shaft to compress the spring 59 to adjust the spring compression and thereby vary the amount of torque necessary to cause the clutch portions 51 and 52 to separate and interrupt the drive of the switch points by the motor 40.

The sprocket 46 driven by the chain 45 is limited to a predetermined amount of turning movement. For this purpose, the sprocket 46 has secured thereto a stop arm 60, FIG. 2, which turns with the sprocket 46 between a pair of stops 61 and 62 secured to a main U-shaped frame member 64. Turning movement of the sprocket 46 in the clockwise direction is limited by the engagement of the stop arm 60 with the stop block 61. When the motor 40 is reversed and the chain 45 is driven in the opposite direction, the stop arm 69 rotates with the sprocket 46 in the counterclockwise direction to bring the stop arm 60 into engagement with the upper stop block 62.

Both the sprocket 46 and the manual throw lever 26 are operable through epicyclic gear means which is preferably in the form of a differential gearing 66, illustrated in FIG. 4. The differential gearing 66 includes an output gear 67, FIG. 4, which is secured to an end of the shaft 36 extending through the rear leg 64B of the U-shaped support bracket 64. As will be pointed out hereinafter, the switch stand means 25, is so constructed that the spring base casting 34 turned by the shaft 36 must be stopped in a generally horizontal position after turning of the spring base'casting 34 through 180 of movement.

As can best be understood from FIG. 4, the sprocket 46 is secured by a tubular member 70 to a differential cage or housing 71 to rotate the cage or housing 71 with the turning of the sprocket 46. Because of the selected gear ratios employed, the stop arm 60 limits the turning of the sprocket 46 to 90; and hence, the differential caging 71 is also limited to a turning of 90.

The differential housing 71 is generally a squared box shaped member having open top and bottom sides with a pair of opposed beveled or miter gears 73 or 74 rotatable on stub shafts 75 and 76, respectively journaled for rota tion in the cage 71, the remaining gear 78 is secured to a shaft 79 which is in turn fastened to the manual throw lever 26.

The manual throw lever 26 is latched in one of its generally horizontal positions by a latch member 81 or 82 each of which is pivotally mounted on a lever rest or stop 83. To latch the manual throw lever 26 resting on one of the stops 83, the latch member 81 is provided over the top surface of the lever 26. The latch members 81 and 82 hold the lever 26 against rotation when the motor 40 is energized to drive the sprocket 46 and the differential 66. The latching of the handle 26 also holds the attached shaft 79 and beveled gear 78 against turning.

The locking of shaft 79 and beveled gear 78 by the latching of the handle 26, is important to hold stationary the gear 78 when the differential housing 71 is rotated by the sprocket 46 and causes the gears 73 and 74 in meshed engagement with the gear 78 to roll about the gear 78 and simultaneously to drive the output gear 67 secured to the shaft 36.

On the other hand, unlatching and turning of the manual throw lever 26 through 180 between the throw lever rests 83 turns the shaft 79 and rotates the attached gear 78 to rotate the gears 73 and 74 which in turn rotate the output gear 67 to turn the shaft 36 to drive the switch stand 25. The differential housing 71 is locked against rotation during the operation of the manual throw lever 26 by means of a brake 85 on the motor 38 which holds the clutch 44, chain 45, sprocket 46 and attached housing 71 against movement during the manual throwing of the switch points.

As apparent from FIG. 4, the differential housing 71 is journalled on its left side by the tubular member 70 in an opening in the upstanding forward wall 64A of the U-shaped bracket 64; and is journaled in the rearward upstanding wall 64A of the U-shaped bracket 64. As seen in FIG. 4, the shaft 79 extends through clearance openings in the sprocket 46, tubular member 70 and the differential housing 71 to turn without rotating these lastnamed elements.

For the purpose of preventing the operation of the electric motor 40 by a remotely generated signal during manual operation of the handle 26, a pair of limit switches and 91 are provided on each of the lever rests 83 to sense the removal of the lever 26 from one of the rests 83.

With removal of the lever 26 from a rest 83, the associated limit switch 90 or 91 opens, and as the other limit switch 90 or 91 is opened, the circuit to the motor 40 is broken and prevents operation of the motor 40. This forestalls operation of the motor 40 with the consequent driving of the switch stand 25 which might cause injury to the person performing the manual operation, particularly where a power operation is unexpected by the person doing the manual operation. When the handle 26 is brought down to a rest 83, the plunger on the associated limit switch 90 or 91 is depressed to prepare for completion of the control circuit for energization of the motor 40.

In a railroad classification yard or the like, it is sometimes desired to return the switch points to their initial position in case there is an obstruction preventing the movement of the switch points to close at their opposite limit position. For example, ener-gization of the motor 40 may cause movement of switch points 12 and 13 until they meet an obstruction, the obstruction would limit further movement of the switch points and turning of the shaft 55. The shaft 55 would hold stationary the output clutch portion 52 causing generation of sufficient 7 overload torque in the clutch 44 to cause its opening of the clutch to operate the limit switch 65. The leaving of the switch points 12 and 13 in an opened condition due to an obstruction could cause derailment.

To prevent an open switch condition due to an obstruction, limit switches 91 and 92 are provided adjacent the stops 61 and 62 to sense completion of movement of the stop arm 60 through a predetermined are which will vary depending on gear ratios, and in this instance, the arc is 90 upon movement of the switch points 12 and 13 from one limit position to another limit position. In the case of an obstruction, the arm 60 would be stopped intermediate one of the stops 61 or 62 whereby both of the limit switches 91 and 92 would be open signifying failure of the switch points to close at the time the limit switch 65 is operated due to an overload condition on the clutch 44. The condition, in which switches 91' and 92' are open and overload switch 65 is operated, can be employed to cause another energization of the motor 40 in the reverse direction to return the switch points 12 and 13 to their original position.

Circuitry for performing such an operation in case of an obstruction can be generally the same as the co-pending application Ser. No. 454,489, now Patent No. 3,363,- 097, of John Roy Wilhelm and Paul E. Redelman. Manifestly, there may be other locations of the switches 91' and 92 for detecting movements of operating elements of the switching apparatus 20 corresponding to arrival of the switch points 12 and 13 at limit positions, e.g., limit switches 91' and 92' could be in the switch stand 25, at the tratfic rails for engagement by the switch points 12 and 13, or at other suitable locations to sense the failure of completion of movement of the switch points 12 and 13 to a limit position.

As stated hereinbefore, the clutch 44 may take a number of forms. Another form is a commercially available torque limiting clutch employing a series of balls which are spring urged into seats to cause a coupling of the input and output sides of the clutch until a predetermined torque is reached at which time the input and output portions separate.

Additional embodiments of the invention are shown in FIGS. 5, 6 and 10. For the embodiments of FIGS. and 6 the operation is the same as hereinbefore described in conjunction with FIGS. 14, except that the chain 45 has been replaced by an eccentric crank arm and connecting slide for operating a disc to turn the differential housing 71. More specifically, in FIG. 5, the output shaft 55, FIG. 5, for the clutch 44 is keyed or otherwise fixedly secured to a crank arm 101. The crank arm 101 is connected by a pin 102 to a connecting rod 103. The connecting rod 103 is formed with an elongated slot 105 in which are disposed a pair of spaced pins 106 and 107 fixed to a turntable disc 108. The disc 108 is secured to the tubular member 70 which, in turn, is secured to the differential housing 71 in the manner described hereinbefore in conjunction with FIG. 4.

The crank arm 101, FIG. 5, is limited in its turning movement by means of stops 110 and 111 secured to a support bracket 112 which is afiixed to the base B. Also, suitable limit switches 115 and 116 on the bracket 112 detect the completion of the movement of the crank 101. Failure of the detection of the completion of the movement by the crank 101 with a simultaneous operation of the overload limit switch 65 signifies an obstruction preventing the closing of switch points 12 and 13 on their initial movement towards a limit postion. The motor 40 may then be automatically reversed to return the switch points to their initial position.

The embodiment shown in FIG. 6 is generally similar to the arrangement shown in FIG. 5, in that it employs a crank arm 101 movable between stops 110 and 111. Arrival of the crank arm 101, FIG. 6, at a stop block 110 or 111 is detected by limit switches 115 and 116. The crank arm 101 in FIG. 6 is secured by a pin 102 to a connecting rod 120 which has a generally rectangular slot 121 in its right hand portion which is received by a block 122. With turning of the crank arm 101 by the motor 40, the connecting rod 120 partakes of a movement such that the block 122 slides within the elongated rectangular slot 121 while exerting a turning movement on the block 122 to rotate the disc 108. The disc 103 is attached to the block 122. Likewise, the disc 108 is attached to the tubular member 70, which, in turn, is attached to the differential housing 71 to turn the differential housing 71 and the output shaft 36 in the manner hereinbefore described.

A brief description of the operation of the switch stand is given hereinafter to aid in the understanding of how the switch stand 25 is effective to hold the switch points in a bias position against the stock rails to assure that the switch points remain closed. Also the description of the switch stand will aliord an understanding of how a locomotive moves the switch points between limit positions when the locomotive trails the switch. The trailing movement of the switch points by the locomotive is unaffected by the prior operation either manually by the throw handle 26 or by the power through the energization of the motor 40.

The switch stand 25 includes an attaching base casting which is secured to the base B and to the railroad ties T. Upstanding from the base 130 is a housing casting 132. The spindle 31 has an upper portion 133 to which is attached a signal flag or light which upon rotating through 90 indicates the condition of the switch points. The spindle 31 is journaled in an upper bearing portion 135 and a lower journal portion 136 of the housing 132. The intermediate portion of the spindle 31 includes a rectangular opening 138 in which slides a crank block 140. A central link 142 extends through the opening 138 in the spindle 138 and is inserted through a central bore in the crank block 140.

As better seen in FIG. 7, an operating linkage 141 for turning the spindle 31 includes the central link 142 secured to a rearward link 146 which is provided on a ball 147 in a bearing element 148. The bearing element 148 is tapered and loosely fitted in a cylindrical bearing seat 149 of the casting 132. The rearward link 146 is secured by a large upstanding pin 150 to the center link 142. Another large pin 151 secures the other end of the center link 142 to a forward link 152. The forward link 152 is pivoted by a pin 153 to a crosshead 154 secured to a spring cap 155. The spring cap 155, FIG. 8, bears on the rightward end of the spring 159 which is mounted on a tapered member and flange 160 on the spring base casting 34. The crosshead 154 is fitted in a rectangular opening in the spring base casting 34.

Thus, turning of the input shaft 36, FIG. 8, turns the spring base casting 34 and the crosshead 154 to turn the linkage 141. Turning of the linkage 141 causes links 152, 142 and 146 to turn in a generally arcuate path causing the crank block 140 to slide overcenter in the rectangular opening 138 in the spindle 31. The overcenter movement of the crank block 140 and linkage 141 causing the spindle 31 to turn through 90. The turning of the spindle 31 turns the crank 30 to move the connecting rod 22 to move the switch points 12 and 13 to a limit position. As the toggle linkage is brought to its horizontal position, the link 152 is thrust rightwardly to cause spring cap 155 to compress the spring 159. The compressed spring 159 exerts a biasing force on the linkage 141 and spindle 31 and through the connecting rod 22 thereby biasing the switch points 12 and 13 in their limit position.

It is important that the block 140 and linkage 141 be stopped in a generally horizontal plane to permit the trailing locomotive to straighten the linkage 141 and to throw the switch points 12 and 13. More particularly, the linkage 141 is able to move through its straight line position that is with the points or pins 147, 150, 151 and 153 all in a straight line, only when the links 146, 142 and 152 are in a horizontal orientation. Movement of a locomotive or car wheel through a switch in the reverse direction causes the connecting rod 22 to pull on the crank to rotate the spindle 31 which turns the block 140. The block 140, as it turns, does not slide vertically from the horizontal in the rectangular opening 138; but straightens the links 146, 142 and 152 with respective pivot points in a generally straight line position while compressing the spring 159 to a large extent. As the locomotive or car wheel continues through the switch, the spring 159 biases the switch points 12 and 13 closed at a limit position and moves the links 146, 142 and 152 from their straight line position.

In lieu of the coupling means 44 in the form of the torque limiting clutch, another embodiment of the invention is illustrated in FIG. 9, which employs a coupling means in the form of an intermittent cam means 160 for coupling the motor 38 to the differential mechanism 48. The differential mechanism 48 operates in the same manner and has the same elements as hereinbefore described and is operable by a hand lever 26 to turn the shaft 79 to cause a manual operation of the output shaft 36 which is connected to the switch stand 25.

Preferably, the intermittent cam means 160 is in the form of a Geneva drive mechanism including a star wheel 164 having a plurality of radially extending slots 165 which are adapted to receive a driving pin 166 carried on a rotatable disc-shaped, driving member 167. The driving member 167 is secured for rotation on a shaft 168 suitably supported in opposed shaft mounts 169 and 170, FIG. 9. Also secured to the shaft 168 is a worm wheel 172 which is disposed in meshed engagement with a worm 173 immediately therebelow. The worm 173 is attached by a coupling means 174 to the motor shaft 150. The worm 173 is on a shaft 176 suitably supported and upstanding members 177 and 178.

Thus, as the motor rotates its shaft 50, the worm 173 turns the worm wheel 172 and shaft 168 to which is affixed the driving member 167 and driving pin 166. The driving pin 166 enters a radial extending slot 164 and engages the side walls along the radial slot 165 to force the star wheel 164 to turn and thereby through the sleeves turn the differential housing 71. The turning of the differential housing 71, with the handle 26 latched in position, causes the opposed .gears 73 and 74 to turn about the stationary gear 78 and thereby rotate the output gear 73 atfixed in the output shaft 36. Thus, the driving pin 166 afiords a driving torque so long as the pin 166 is within one of the driving slots 165. However, as soon as the pin 166 leaves the driving slot 165, the turning of the star wheel 164 is finished.

It is preferred to lock the star wheel 164 against reverse turning and to assure that the star wheel 164 has driven through a precise increment necessary to move the switch stand linkage to its horizontal position. For this purpose, the driving member 167 is provided with a circular cam 180, which has a curvature complementary to the arcuate curvatures 181 on the outer periphery of the star wheel 164 between the radial slots 165.

Thus, after the driving pin 166 leaves one of the radial slots 165, the cam 180 moves its curved surface into engagement with the complementary curved surface 181 of the star wheel 164 to lock the same against movement and to assure the precise positioning of the star wheel for the next operation. It will be appreciated that the cam 180 may move the star wheel 164 precisely to locate the same after the pin 166 has moved the star wheel 164 to its general position.

It will be appreciated that the motor 40 need not be stopped precisely in order to limit the turning of the switch stand spindle 31 since the driving pin 166 is free of rotating the star wheel 164 for a considerable period after leaving a radial slot 165. Even with the ear reduction afforded by the worm 174 and 172, it is still difiicult to afford large amounts of driving force to drive the 10 switch points and still uncouple the driving force when the switch points are at a limit position.

With the embodiment of the invention of FIGS. 8 and 9, contacts (not shown) may be associated with the motor 40 to control the amount of rotation thereof. As the motor 40 is de-energized and brought to a stop, its inertia may cause movement of the driving pin 166 after it has left a radial slot 165. However, the driving pin 166 may overtravel without changing the position of the switch points 12 and 13. Thus, the Geneva drive mechanism may drive the linkage 142 and spindle 131 to precise horizontal positions in a positive manner without necessity for precisely stopping the motor 40.

The torque limiting clutch 44 is preferred to the Geneva drive mechanism inasmuch as the clutch is better adapted for rapid reversal of the driving of the switch points. It will be appreciated that the driving pin 166 will be at a spaced distance from the slot because of overtravel from its previous operation. Thus, during a subsequent energization of the motor 40, irrespective of the direction of rotation of the motor '40, the drive pin 166 is moving toward a slot 165. This results in a slight time lag. Moreover, the driving force provided by the Geneva driving mechanism varies as the pin 166 moves radially into the slot 165 and close to the center of the star wheel 164.

From the foregoing, it will be seen that the present invention affords a quickly operating switching apparatus capable of being operated by the three different modes, namely, power operation, manual operation or by a trailing car or locomotive Wheel. Also it will be seen that an electric motor may be employed and a coupling means may be provided to afford a positive torque and drive to move the switch points quickly, and to a completely closed limit position. Moreover, the coupling means limits or uncouples the drive of the motor 40 from the switch points after they have reached a limit position even though the amount of movement of the switch points is a relatively small amount of movement.

Although in the preferred embodiment of the invention, the motor means 38 preferably employs an electric motor 40, it is to be understood that hydraulic air or other types of motors could be employed to drive a gear means through a coupling means to shift the switch points and still be within the purview of the principles of the present invention.

Hence, while preferred embodiments of the invention have been described and illustrated, it is to be understood that they are capable of variation and modification, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the following claims.

We claim:

1. In a switching apparatus for shifting switch points between limit positions, connecting means for connecting to said switch points for shifting of said switch points by said switch apparatus, gear means connected to said connecting means for actuating said connecting means to shift said switch points; manual throw lever means connected to said gear means for operating said gear means to shift said switch points thereby affording a manual switching operation, and power operating means for operating said switch points, said power operating means including a motor means of the reversing type for driving said switch points and a torque limiting clutch for coupling the drive of said motor means to said gear means, said clutch havmg an input driving portion connected to said motor means and an output portion connected to said gear means, the drive of said motor means being interrupted when said switch points have shifted from one limit position to another limit position, said portions of the clutch separating in the event the switch points encounter an obstruction preventing attainment of a limit position, and means to sense clutch separation and condition the motor for a reverse drive to return the switch points to their original position upon the occurrence of the obstructing event.

2. The switching apparatus of claim 1 wherein said input and output portions of said torque limiting clutch are disposed for movement relative to one another, said output portion and said input portion of said torque limiting clutch being axially movable relative to one another when the torque limit is reached.

3. The apparatus of claim 1 wherein said motor means is an electric motor reversible in its direction of rotation, and wherein stop means stop the rotation of said output portion of said clutch after a predetermined amount of movement in each of its directions of rotation.

4. In a switching apparatus for throwing railroad switch points between limit positions with railroad stock rails, switch stand means having a generally vertical spindle for operative connection to said switch points to move said switch points relative to said stock rails with turning of said spindle, said switch stand means having means including a linkage for turning said spindle, gear means connected to said last-mentioned means for turning said linkage, reversible motor means for connection to said gear means to drive said switch points between limit positions, coupling means including a torque limiting clutch to couple said motor means to said gear means for operating said gear means to turn said linkage and said spindle to throw said switch points, said coupling means interrupting the drive of said switch points by said motor means after said spindle has turned through a predetermined amount of rotation, said clutch having an input portion driven by said motor means and an output portion for driving said gear means, said portions of the clutch separating in the event the switch points encounter an obstruction preventing attainment of a limit position, and means to sense clutch separation and condition the motor for a reverse drive to return the switch points to their original position upon occurrence of the obstructing event.

5. The switching apparatus of claim 4 including stop means to stop the rotational movement of said gear means by said clutch and thereby stop the rotational movement of said switch stand spindle and said switch stand linkage, said switch stand linkage being stopped in a predetermined orientation for movement by said spindle when a locomotive or car wheel trails said switch, manually operable throw means connected to said gear means to shift said switch points, and means to arrest said manually operable throw means with said switch stand linkage in said predetermined orientation.

6. The switching apparatus of claim 5 wherein said clutch drives said gear means and turns said spindle until said stop means limits turning of said gear means.

7. The switching apparatus of claim 5 wherein said gear means include a differential gear means, said differential gear means having a first gear connected to manu- 55 ally operable throw means, a second gear connected to said linkage of said switch stand, gear cage means for turning by said clutch, and an opposed pair of gears journaled for rotation in said gear cage means and meshed with said first and second gears.

8. The switching apparatus of claim 5 including sensing means to sense the throwing of said switch points by said manually operable throw means and effective to disable a concurrent operation of the stand by said motor means.

9. The switching apparatus of claim 5 including switch means for detecting failure of said switch points to reach one of said limit positions.

10. In a switching apparatus having a reversible motor means for shifting switch points between limit positions, connecting means for connection to said switch points for shifting said switch points between limit positions, clutch means for coupling said motor means to said connecting means, said clutch means having an input portion connected to said motor means, said clutch means having an output portion connected to said connecting means, said input and output portions of said clutch means being separable at a predetermined amount of torque, and sensing means for detecting clutch separation and effective to control said motor means when said predetermined amount of torque is reached.

11. The switching apparatus of claim 10 including stop means for limiting the turning movement of the output portion of said clutch means to a predetermined amount of turning movement with arrival of the switch points at a limit position, detecting means for detecting said predetermined amount of movement of said switch points I and arrival of the switch points at a limit position, said sensing means and said detecting means causing reversal of said motor means to return the switch points to the original limit position upon sensing said predetermined amount of torque and detecting failure of the switch points to move to the intended limit position because of an obstruction preventing movement of the switch points to the intended limit position by said motor means.

References Cited UNITED STATES PATENTS 3,355,585 11/1967 Schwab. 3,158,345 11/1964 Wilhelm. 2,852,667 9/1958 Haines. 2,829,851 4/1958 George. 1,366,350 l/1921 Beil 246240 1,923,568 8/1933 Bone 246-240 2,986,630 5/ 1961 Maynard 24624O 3,136,509 6/ 1964 Magnus 246242 ARTHUR L. LA POINT, Primary Examiner.

R. A. BERTSCH, Assistant Examiner.

US. Cl. X.R. 

